(AP/CBS) - More than a week since announcing his decision that the United States should -- with the approval of Congress -- launch a military strike against Syrian President Bashar Assad for his alleged use of chemical weapons, President Obama on Tuesday night told the American public that the threat of a military strike should stay on the table while the U.S. and its allies take more time to pursue a diplomatic resolution with Assad.

"Sometimes resolutions and statements of condemnation are simply not enough," Mr. Obama said in a televised address from the East Room of the White House. "Our ideals and principles, as well as our national security, are at stake in Syria."

Mr. Obama said that, given Syria's recent offer to give up its chemical weapons, he's asked the leaders of Congress to postpone their vote on the use of force. The administration will work with its allies in the United Nations, he said, to put forward a resolution requiring Assad to give up the weapons. The international community will also give U.N. inspectors an opportunity to report their findings on the use of chemical weapons in Syria.

In the meantime, Mr. Obama said, he's ordered the U.S. military to "be in a position to respond" in case diplomatic efforts fail.

"For nearly seven decades the United States has been the anchor of global security," he said. "This has meant more than forging international agreements, it has meant enforcing them."

Acknowledging the skepticism and concern among the public over the prospect of a military strike, the president explained why intervening in Syria is in the nation's interest. Mr. Obama asserted, "We know the Assad regime was responsible" for an apparent chemical weapons attack on August 21 that killed more than 1,000 people outside of Dasmascus, in what Mr. Obama called "a violation of the laws of war."

"If we fail to act, the Assad regime will see no reason to stop using chemical weapons," the president said. "Over time our troops would again face the prospect of chemical warfare on the battlefield."

Chemical weapons could fall into the hands of terrorists or threaten American allies neighboring Syria, he said. A failure to act, he added, could weaken prohibitions against other weapons of mass destruction, potentially emboldening Iran to continue developing its nuclear weapons capabilities.

"This is not a world we should accept," Mr. Obama said. "This is what's at stake."

The president also addressed the fast-moving diplomatic developments in Syria. As recently as Sunday, in an interview with Charlie Rose, Assad refused to even acknowledge the existence of his chemical weapons stockpile. By Tuesday, however, Syrian officials said they were interested in accepting a Russian proposal to avert a U.S. strike by relinquishing its chemical weapons to the international community and signing the Chemical Weapons Convention.

"Over the last few days we've seen some encouraging signs," Mr. Obama said, noting that they followed his "constructive talks" with Russian President Vladimir Putin on the sidelines of the G-20 Summit last week.

"It's too early to tell whether this offer will succeed," he said. However, he added, it "has the potential to remove the threat of chemical weapons without the use of force."

The president's prime-time address followed weeks of intense engagement with Congress over a possible military strike. On Tuesday, Mr. Obama went to Capitol Hill to meet separately with the Senate Democratic Caucus and the Senate Republican Conference, spending more than an hour with each group.

In that meeting, according a senior administration official, the president told lawmakers his administration would work with Congress to craft language for the authorizing resolution that would strengthen the diplomatic efforts underway. The president also told senators Tuesday that he was pleased with the seriousness of the public debate that has taken place since he announced he would seek congressional approval for a military strike.

In spite of that ongoing debate -- and efforts from several high-level administration officials to explain the need for Congress to authorize the use of military force -- the idea of using military force in Syria has up to this point found little support in Congress or among the public.

In his address Tuesday night, Mr. Obama acknowledged the many letters he's received from citizens worried about the prospect of another military engagement in the Middle East, and he addressed point-by-point many of the concerns raised.

"Many of you have asked, won't this put us on a slippery slope to another war?" Mr. Obama said, recalling a letter from a veteran who said the nation is "sick and tired of war." The president promised he would not put "boots on the ground" in Syria, nor would he pursue an open-ended campaign -- or even a prolonged air campaign as took place in Libya.

"This would be a targeted strike to achieve a clear objective, deterring the use of chemical weapons and degrading Assad's capabilities," he said.

"Let me make something clear," he responded. "The United States military doesn't do pinpricks. Even a limited strike will send a message to Assad that no other nation can deliver."

As for concerns that weakening the Assad regime could strengthen al Qaeda forces in Syria, Mr. Obama said, "Al Qaeda will only draw strength in a more chaotic Syria if people there see the world doing nothing to prevent innocent civilians from being gassed to death."

He added that "the majority of the Syrian people, and the Syrian opposition we work with, just want to live in peace, with dignity and freedom. And the day after any military action, we would redouble our efforts to achieve a political solution that strengthens those who reject the forces of tyranny and extremism."

The president made the case that military intervention aligned with both liberal and conservative values.

"To my friends on the right, I ask you to reconcile your commitment to America's military might with the failure to act when a cause is so plainly just," he said. " To my friends on the left, I ask you to reconcile your belief in freedom and dignity for all people with those images of children writhing in pain and going still on a cold hospital floor."

Those congressmen mostly adamantly opposed to military action said they were not swayed. "Pres. Obama's speech didnt convince me," Sen. Rand Paul, R-Ky., said via Twitter.

Rep. Jason Chaffetz, R-Utah, said on Twitter, "Still no explanation of steps 2, 3, 4, etc. and consequences of going to war in Syria. I am still a NO."

Sens. John McCain, R-Ariz., and Lindsey Graham, R-S.C., who have called for stronger intervention in Syria than Mr. Obama is calling for, said in a joint statement that they appreciated the president's remarks but regretted "that he did not speak more forcefully about the need to increase our military assistance to moderate opposition forces in Syria."

They added, "We also regret that he did not lay out a clearer plan to test the seriousness of the Russian and Syrian proposal to transfer the Assad regime's chemical weapons to international custody."

Other members of Congress said the president put forward a strong argument for action.

"Pres. Obama's leadership brought diplomatic solutions back to the table, shows his willingness to exhaust every remedy before use of force," House Minority Leader Nancy Pelosi, D-Calif., said on Twitter.

Rep. Jan Schakowsky, D-Ill., said in a statement, "President Obama tonight made a clear and compelling case as to why we cannot sit by as the Assad regime uses chemical weapons against its people."

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